Optical diffuser having frit based coating with inorganic light diffusing pigments with variable particle size therein

Abstract

A diffuser is provided that includes a glass substrate with a diffusing coating thereon. The diffusing coating may include one or more layers. In certain example embodiments, the diffusing coating comprises inorganic pigments therein for light diffusing purposes, and the inorganic pigments are sized so as to permit a diffuser having a combination of high visible transmission and good diffusion qualities to be realized. In certain example embodiments, the diffusing coating may be of or include a frit with the inorganic pigments therein.

1. An illumination system comprising:
 a light source for emitting light, the light emitted from the light source including at least visible light and ultraviolet (UV) radiation; 
 a diffuser positioned so as to receive light from the light source, the diffuser diffusing visible light received from the light source towards another element of the illumination system; 
 wherein the diffuser comprises a glass substrate, with a light diffusing coating formed on an external surface of said glass substrate, the light diffusing coating comprising inorganic pigment particles mixed with frit; and 
 wherein the diffuser has a diffusing property F(Q) of greater than 0.100 and a visible transmission of at least 57%, where F(Q) is defined by:
     F ( Q ) =1/[4({θmax−θmin}/ W ) 2 +1] 
 
 wherein W is a half width at a half maximum value point of a illumination vs. diffusing angle plot, θmax is a maximum value of the illumination vs. diffusing angle plot, and θmin is a minimum of at least one of the tails of the illumination vs. diffusing angle plot, wherein 
 the average particle size of the inorganic pigment particles is no greater than 0.5 microns, and the thickness of the diffusing coating is from about 1.0 to 7.0 microns. 
 
     
     
       2. The illumination system of  claim 1 , wherein the diffuser has a diffusing property F(Q) of greater than 0.102. 
     
     
       3. The illumination system of  claim 1 , wherein the diffuser has a diffusing property F(Q) of greater than 0.110. 
     
     
       4. The illumination system of  claim 1 , wherein the diffuser has a diffusing property F(Q) of greater than 0.125. 
     
     
       5. The illumination system of  claim 1 , wherein the diffuser has a diffusing property F(Q) of greater than 0.200. 
     
     
       6. The illumination system of  claim 1 , wherein the diffuser has a visible transmission of at least about 58%. 
     
     
       7. The illumination system of  claim 1 , wherein the diffuser has a visible transmission of at least about 60%. 
     
     
       8. The illumination system of  claim 1 , wherein the diffusing coating comprises from about 0.25-20%, by weight, of the inorganic pigment particles. 
     
     
       9. The illumination system of  claim 1 , wherein the inorganic pigment particles comprise one or more of cerium dioxide, titanium dioxide, zinc oxide, and titanium dioxide. 
     
     
       10. The illumination system of  claim 1 , wherein the diffusing coating comprises at least about 80% of the flit by weight. 
     
     
       11. The illumination system of  claim 1 , wherein the diffuser further comprises a UV blocking coating so that the diffuser has a T UV  (UV transmission) of no greater than about 5%, more preferably no greater than about 2%. 
     
     
       12. The illumination system of  claim 1 , wherein the diffusing coating is in direct contact with the glass substrate. 
     
     
       13. The illumination system of  claim 1 , wherein the diffusing coating comprises at least about 90% of the frit by weight. 
     
     
       14. An illumination system comprising:
 a light source for emitting light; 
 a diffuser positioned so as to receive light from the light source, the diffuser diffusing visible light received from the light source towards another element of the illumination system; and 
 wherein the diffuser comprises a glass substrate, with a light diffusing coating formed on an external surface of said glass substrate, the light diffusing coating comprising inorganic pigment particles mixed with glass frit; and 
 wherein the diffuser has a diffusing property F(Q) of greater than 0.100 and a visible transmission of at least 57%, where F(Q) is defined by:
     F ( Q ) =1/[4({θmax−θmin}/ W ) 2 +1] 
 
 wherein W is a half width at a half maximum value point of a illumination vs. diffusing angle plot, θmax is a maximum value of the illumination vs. diffusing angle plot, and θmin is a minimum of at least one of the tails of the illumination vs. diffusing angle plot, wherein 
 the average particle size of the inorganic pigment particles is no greater than 0.5 microns, and the thickness of the diffusing coating is from about 1.0 to 7.0 microns. 
 
     
     
       15. The illumination system of  claim 14 , wherein the diffuser has a diffusing property F(Q) of greater than 0.102. 
     
     
       16. The illumination system of  claim 14 , wherein the diffuser has a diffusing property F(Q) of greater than 0.125. 
     
     
       17. The illumination system of  claim 14 , wherein the diffuser has a visible transmission of at least about 58%. 
     
     
       18. The illumination system of  claim 14 , wherein the diffusing coating comprises from about 0.25-20%, by weight, of the inorganic pigment particles. 
     
     
       19. The illumination system of  claim 14 , wherein the inorganic pigment particles comprise one or more of cerium dioxide, titanium dioxide, zinc oxide, and titanium dioxide. 
     
     
       20. The illumination system of  claim 14 , wherein the diffusing coating comprises at least about 80% of the frit by weight. 
     
     
       21. The illumination system of  claim 14 , wherein the diffusing coating is in direct contact with the glass substrate. 
     
     
       22. The illumination system of  claim 14 , wherein the diffusing coating comprises at least about 90% of the frit by weight.